Incandescent lamp



March 15 1927.

' 1,621,360 R. N. FALGE` I'NCANDESCENT LAMP Filed April 22, 1922 figaJNYEAZT :7H HUBERT AZ'. Ear, 5E',

ROBERT N. EALGE, E CLEVELAND, oHIo, AssIGNoR 1 prevent the f lthefilament. -.\\v

Patented M ar. 15, 19)27.

UNITED, STATES vPfr.rieur QFFICE.

To GENERAL ELECTRIC. CoM-v .PANY, .A CORPORATION 0F NEW YORK.

INGANDESCENT LAMP.

Applicatitm` filed April 2.2, 1922. Serial No. 556,080.

I My invention relates to electric incandescent lamps for projectionpurposes and more especially to such lamps for use in automobile orother vehicle headlamps, though my invention is of advantage in anyrcase where, glare is objectionable. It has been the practice in mostcases to use clear glass bulbs for suchilamps and, because suchconstruction is desirable from. the standpoint of manufacture and onaccount of the p-ossession of desirable characteristics such as greaterstrength and freedom from strain, such bulbs have been made with vthefront portion thereof conforming substantially to the surface of asphere. is accurately positioned in' the'center of'such sphere, noparticular trouble arises. 'However, if the filament is not at thecenter, the

image of the filament is not reflected backv ,upon the filament from thefront portion of the bulb but is reflected back to a position at' oneside of the filament and this causes trouble. No-glare devlcesrwlnch areused,

for instance in automobile headlamps, ordiynarily require a definiteposition of the'light source and the creation of a secondary lightsourcespaced fro'm the filament 1.cnds,'ob' viously, to cause suchdevices to fail ,in their function. The result is a glaring spot whichappears on: the reflector. .A similargresult Y will `also'bev obtainedwhere `the bulb departs slightly fromthe spherical contour although thefilament may be accurately positioned. In both cases the trouble ariseschiefly from the fact that amore or less definite image lof the filamentis reflected ba'ck. l The object Vof my invention'7 is to correct this'trouble.

' According to my ferred form ay applied to bulbs of the usual shape,the bin is rippled so asto cause the `light rays which are. reflectedback from the` substantially spherical front portion to followmultitudinous directions, or in other mords, to dis` erse or r1 ationofa definite image of In the drawing Figure 1 .is a partially verticalsection showing a lamp embodying my invention, lsuitably mountedin apara- `When the filament 'rugation or rippling of the bulbV isinvention',; in its prediffuse the same and" of the same; Fi 3 is a planpartially in section showing t e lamp and indicating Vthe directionstaken by the reflected rays; Fig. 4 is a front elevation of the'same;Figs. 5

`and 6 arel similar views of a modification;

and Fig. 7 is a View showing diagrammati- `cally the reflection of lightrays-1n a lamp as heretoforeconstructed.'v

Referring to the drawi g, 10 is the bulb of an electric incandescentlamp having tlie usual base 11, said lamp being mounted in ay bolic'reflector; Fig. 2 isa front elevation headlamp of which is shown theparabolic Y reflector 12. The filament of the lamp is shown at L13. Thefront portion of the said bulb, which is substantially a portion of asphere, is covered with a series of corrugations or' ripples 14 whichmay be concentric as shown. In Fig. 3 the effect of vsuch core shown.'lhat portion of the light rays Which-is relflected back from the frontsurface `of' the bulhis dispersed or diffused and this prevents theformation of a definite imageof the filament. In Figs: 5 and f5 isillustrated a modification in wluch the front of the bulb is fiattened,and it'is provided' with corrugations or rip les. In Fig. 7 isillustrated the undesirab e results obtained with the construction ofbulb heretofore used. The filament 13 in this particular case happens tobe offset from the center 15 of the spherical front portion ofthe bulb.`Y Thisresjults in the formation of a definite vimage 16 of t-hefilament, which, as hereinbefore explained, tends to cause objectionableglare.

What I claim as new and desire to secure An electric incandescentlampfor ve- ,hicleheadlamps comprising a base, a concentrated filament. and.a clear lglass v bulb vbyjLetters Patint of the d/nited States, is vhicle head-lamps comprising a base, a conri ples so as to prevent theback reiection centrated filament and a. clear glass bulb o a definiteimage of the filament withoutv having its wall of substantially uniforma'ectingl appreoiably the light transmitted 10 A thickness throughoutaiid having that portherethrough. 5 tion thereof opposite to the base ofthe lamp In Witness Whereof, I have hereunto set of 'Substantillyspherical contour Ibut havmy hand this 20 day ofvApril, 1922. ingthereon a, plurality of slight concentricY l ROBERT N. FALGE.

